From: Shakeel Butt shakeelb@google.com Subject: mm/list_lru.c: fix memory leak in __memcg_init_list_lru_node

Syzbot reported following memory leak:

ffffffffda RBX: 0000000000000003 RCX: 0000000000441f79 BUG: memory leak unreferenced object 0xffff888114f26040 (size 32): comm "syz-executor626", pid 7056, jiffies 4294948701 (age 39.410s) hex dump (first 32 bytes): 40 60 f2 14 81 88 ff ff 40 60 f2 14 81 88 ff ff @`......@`...... 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<0000000018f36b56>] kmemleak_alloc_recursive include/linux/kmemleak.h:55 [inline] [<0000000018f36b56>] slab_post_alloc_hook mm/slab.h:439 [inline] [<0000000018f36b56>] slab_alloc mm/slab.c:3326 [inline] [<0000000018f36b56>] kmem_cache_alloc_trace+0x13d/0x280 mm/slab.c:3553 [<0000000055b9a1a5>] kmalloc include/linux/slab.h:547 [inline] [<0000000055b9a1a5>] __memcg_init_list_lru_node+0x58/0xf0 mm/list_lru.c:352 [<000000001356631d>] memcg_init_list_lru_node mm/list_lru.c:375 [inline] [<000000001356631d>] memcg_init_list_lru mm/list_lru.c:459 [inline] [<000000001356631d>] __list_lru_init+0x193/0x2a0 mm/list_lru.c:626 [<00000000ce062da3>] alloc_super+0x2e0/0x310 fs/super.c:269 [<000000009023adcf>] sget_userns+0x94/0x2a0 fs/super.c:609 [<0000000052182cd8>] sget+0x8d/0xb0 fs/super.c:660 [<0000000006c24238>] mount_nodev+0x31/0xb0 fs/super.c:1387 [<0000000006016a76>] fuse_mount+0x2d/0x40 fs/fuse/inode.c:1236 [<000000009a61ec1d>] legacy_get_tree+0x27/0x80 fs/fs_context.c:661 [<0000000096cd9ef8>] vfs_get_tree+0x2e/0x120 fs/super.c:1476 [<000000005b8f472d>] do_new_mount fs/namespace.c:2790 [inline] [<000000005b8f472d>] do_mount+0x932/0xc50 fs/namespace.c:3110 [<00000000afb009b4>] ksys_mount+0xab/0x120 fs/namespace.c:3319 [<0000000018f8c8ee>] __do_sys_mount fs/namespace.c:3333 [inline] [<0000000018f8c8ee>] __se_sys_mount fs/namespace.c:3330 [inline] [<0000000018f8c8ee>] __x64_sys_mount+0x26/0x30 fs/namespace.c:3330 [<00000000f42066da>] do_syscall_64+0x76/0x1a0 arch/x86/entry/common.c:301 [<0000000043d74ca0>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

This is a simple off by one bug on the error path.

Link: http://lkml.kernel.org/r/20190528043202.99980-1-shakeelb@google.com Fixes: 60d3fd32a7a9 ("list_lru: introduce per-memcg lists") Reported-by: syzbot+f90a420dfe2b1b03cb2c@syzkaller.appspotmail.com Signed-off-by: Shakeel Butt shakeelb@google.com Acked-by: Michal Hocko mhocko@suse.com Reviewed-by: Kirill Tkhai ktkhai@virtuozzo.com Cc: stable@vger.kernel.org [4.0+] Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/list_lru.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/list_lru.c~list_lru-fix-memory-leak-in-__memcg_init_list_lru_node +++ a/mm/list_lru.c @@ -354,7 +354,7 @@ static int __memcg_init_list_lru_node(st } return 0; fail: - __memcg_destroy_list_lru_node(memcg_lrus, begin, i - 1); + __memcg_destroy_list_lru_node(memcg_lrus, begin, i); return -ENOMEM; }

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